Method of preparing stable liquid perfume material mixtures with a high solids content

ABSTRACT

Method of preparing homogeneous mixtures of liquid and/or solid perfume materials by mixing the components and liquefying the mixture, in which a binary or ternary eutectic premix which is liquid at room temperature and contains 10-90% of the individual substances in the case of binary mixtures and 10-70% in the case of ternary mixtures is formed from 
     a) the solid 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene, 
     b) the solid or oily α,n-hexylcinnamaldehyde, 
     c) the oily p-tert-butyl-α-methylhydrocinnamaldehyde, 
     d) the solid p-methoxyacetophenone and 
     e) the solid benzyl o-hydroxybenzoate, 
     and the remaining solid and liquid products are introduced into this mixture simultaneously or in a sequence which is freely chosen for the particular mixture and is independent of the chemical and physical nature of the substances, and the binary and ternary eutectic premixes prepared in this manner.

This application is a 371 of PCT/EP 93/00014, filed Jan. 7, 1993.

The invention relates to a novel method of preparing homogeneous liquidmixtures of solid perfume materials and the use of these mixtures forpreparing solvent-free ready-made perfume formulations.

For application reasons (e.g. stability, odor intensity orsubstantivity), solids are being increasingly used in the modern perfumeindustry. These substances are indispensable in particular for perfumesfor detergents and softeners, since these products are subjected toconsiderable stresses during preparation, in the market and subsequentlyduring processing. The fragrance of these products is not only ofdecisive importance in decisions for or against the purchase of acertain product but also accompanies the product from production throughstorage to use. In addition, the laundry which has been washed ortreated with a softener must have a pleasant odor--even after weeks ofstorage--in order to meet the high quality expectations of the buyer ofa branded article.

The problem of these extreme quality requirements with regard to amodern ready-made perfume is illustrated by the fact that about 99.9% ofthe industrial perfume used "disappears" in the wastewater in thewashing or softening process, while only about 0.1% is absorbed by thewashed laundry.

For mixing perfume materials, the chemically stable, liquid componentsare usually initially introduced, as a rule with the addition of furthersolvents, such as dipropylene glycol (DPG) and diethyl phthalate (DEP)and the like, and the solid components are added gradually with vigorousstirring, the mixture being heated externally or by means of internalheating coils until the solids melt or go into solution. Since theheating surfaces have to be heated to relatively high temperatures inorder to achieve sufficient heat transport, a certain amount of damageoccurs at these heating surfaces as a result of overheating,particularly in the case of sensitive substances. Moreover, the vigorousmixing results in greater contact with air, so that it is necessary towork under an expensive inert gas atmosphere in order to avoid damage byoxidation.

After dissolution of the solids, the mixture is cooled. Sensitive,readily volatile or chemically unstable materials are then added withgentle stirring, and stirring is continued until the mixture ishomogeneous. This method is considerably time-consuming since adisadvantageous solid/liquid mixing ratio is initially present or atime-consuming heating and cooling process is necessary in between andthe use of additional solvents not only incurs costs and unnecessarilyincreases the processing quantities but also additionally pollutes theenvironment.

DE-A 39 22 389.2 describes a process in which the introduction of thesolid materials into the liquid substances is carried out withsimultaneous addition of an inert gas to the stirring zone, with theresult that the damage which occurs due to overheating and mechanicalstressing of the sensitive materials is completely avoided.

However, it proves to be disadvantageous that the proportion of solidsubstances in conventional perfume formulations is in fact comparativelyhigh and that such substances may be difficult to meter and convey andfurthermore, as powders, occupy large volumes, giving rise to transportand storage problems. As a remedy, such substances are in some casestherefore dissolved in suitable solvents and thus converted into theliquid state, with the result that metering and handling are simplified.However, this has the disadvantage that the total amount is greatlyincreased due to the amounts of solvent, with the result that transportand storage once again become expensive and in addition solvents areintroduced into the formulation, which not only constitute a cost factorthemselves but are also to be classified as causing environmentalpollution.

The above-mentioned solid contents of 20-60% of the total perfumemixture are composed of, in each case, about 20 different materials,which in turn are selected from about 100 conventional materials,depending on the desired fragrance note. 5 of these substances, namely6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene,α,n-hexylcinnamaldehyde, p-tert-butylmethylhydrocinnamaldehyde,p-methoxyacetophenone and benzyl o-hydroxybenzoate, which occur invirtually all formulations, although in different amounts, account foras much as over 70% of the total amount. Together with the 10 next mostfrequent substances, the amount increases as much as over 90%. The next10 substances in terms of quantity increase the amount to over 95%. Allother substances are present only in amounts of less than 0.5%, so thatadmixing them presents no problems.

In order to avoid the disadvantages in the processing of solids, it istherefore the object to convert these substances or at least the maincomponents into the liquid state and to provide them in this form, evenafter prolonged storage, for the final mixing process.

Relatively long-term storage above the particular melting point is outof the question not only because of the costs but in particular forstability and quality reasons. Dissolution in solvents having a "neutralodor", such as diethyl phthalate (DEP) or dibutyl glycol, dipropyleneglycol (DPG) and similar solvents, which is practiced in some cases forcomponents present in insignificant amounts, is of course out of thequestion for products present in major amounts, because as a result toolarge an amount of solvents which pollute the environment and harm theproduct are introduced into the formulation.

Prior dissolution in the "liquid" components of the formulations is notpossible because, if they occur in relatively large amounts, for examplephenylethyl alcohol, they are poor solvents, or they are used only inrelatively small ratios which change for the different formulations, sothat prior dissolution is not suitable owing to the associated storageand logistic problems.

Surprisingly, it has now been found that the above-mentioned solid orviscous main products can be combined to give binary and ternarymixtures (fragrance building blocks) which have a low viscosity not onlyat room temperature but, in some cases, also down to 0° C. or -20° C.,and that virtually all commonly used industrial perfume formulations canbe prepared without the addition of solvents by combining thesefragrance building blocks in suitable ratios.

These liquid mixtures, which are still liquid at temperatures of 30°-80°C. below the melting point of the components, i.e. in some cases at -20°to 0° C., are referred to below as "eutectic mixtures" in order toindicate the unexpectedly low freezing point compared with theindividual components. Whether particular solid phases mix with oneanother or not, i.e. whether true eutectic mixtures are present, was notinvestigated or taken into account.

Properties of the materials

1. 6-Acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene

White crystalline powder, melting point (according to purity) 55°-60°C., commercial purity 95-99.8%, binds foreign odors very readily, highsubstantivity, relatively poorly soluble in liquid perfume materials,readily soluble in diethyl phthalate and alcohol, musk odor.

2. α-Hexylcinnamic aldehyde (HCA)

Solid at 10°-23° C. At higher temperature, yellowish, oily liquid whichhas a high tendency to oxidation (cinnamic acid). Dissolves readily indiethyl phthalates and dipropylene glycol, floral, fruity note.

3. Benzyl salicylate (BSA)

Crystalline mass which melts at about 25°-30° C. to give a colorlessoily substance. Soluble in diethyl phthalate, poorly soluble indipropylene glycol. Sweet-floral, slightly balsamic odor of lowintensity.

4. p-Methoxyacetophenone or methyl 4-methoxyphenyl ketone (PMA)

Colorless crystals which tend to agglomerate. Melting point 36°-40° C.Typically floral-sensual intense odor, poorly soluble in liquid perfumematerials, dipropylene glycol, readily soluble in diethyl phthalates andalcohol.

5. p-tert-Butyl-α-methylhydrocinnic aldehyde (PTB)

Colorless, oily liquid, dissolves in alcohol and other perfume oils anddiethyl phthalates. Fresh aldehydic floral odor, very sensitive tooxidation, solidifies to the solid carboxylic acid (cinnamic acidderivative), risk of autoxidation and spontaneous ignition, iseliminated in a mixture with other suitable perfume materials.

The short designations appended above in parentheses are used in thetext below.

As binary or multi-substance mixtures, the mixtures of the stated 5individual materials, proposed according to the invention, exhibit, inwide mixing ratios, a surprisingly pronounced melting point depressionin conjunction with excellent thermal stability and chemical stabilityto oxidation and polymerization. In all cases, stable liquids are formedby mixing two or more of the stated substances in the specified ratios.These liquids can be metered without problems via pumps and valves as"fragrance building blocks" with the other liquid materials withoutfurther pretreatment at temperatures of 10°-20° and can be furtherprocessed in simple mixers to give ready-made perfume formulations.

In some cases, surprising "superstability" was obtained since somemixtures still remain liquid (of low viscosity to medium viscosity) evenon prolonged storage in temperature ranges from minus 18° to minus 20°C. Even the addition of seed crystals does not cause these mixtures tocrystallize. The individual results obtained are shown in the Tablesbelow, the following classification being used:

1=Solidifies directly after cooling

2=Solidifies completely after one day

3=Solidifies partly after one day

4=Solidifies completely after 3 days

5=Solidifies partly after 3 days

6=Does not solidify after 3 days

In some cases, the viscosity was measured at 20° C. Corresponding valuesin mPa.s are likewise shown in the Tables below.

    __________________________________________________________________________    Mixture of 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydro-                         naphthalene (AHN), hexylcinnamaldehyde (HCA) and p-tert-                      butyl-α-methylhydrocinnamaldehyde (PTB)                                     Parts                                                                     AHN HCA  PTB Visc.                                                                             -20° C.                                                                      0° C.                                                                       +10° C.                                                                      +20° C.                              __________________________________________________________________________    40  10   50      5     5    6     6                                           40  20   40      6     6    6     6                                           40  30   30  32  6     6    6     6                                           40  40   20      6     6    6     6                                           40  50   10      4     4    6     6                                           50   5   45      4     4    6     6                                           50  15   35  42  6     6    6     6                                           50  25   25  42  6     6    6     6                                           50  35   15      4     4    5     6                                           50  45    5      4     4    5     6                                           60  10   30      6     6    6     6                                           60  20   20  53  6     6    6     6                                           60  30   10      4     5    5     6                                           __________________________________________________________________________    Mixture of 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydro-                         naphthalene (AHN) and p-methoxyacetophenone (PMA)                                   Parts                                                                   AHN   PMA Visc.                                                                              -20° C.                                                                     0° C.                                                                         +10° C.                                                                     +20°  C.                               __________________________________________________________________________    25    75       1    2      2    5                                             50    50  27   1    2      3    6                                             75    25       1    2      2    5                                             __________________________________________________________________________    Mixture of 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydro-                         naphthalene (AHN) and hexylcinnamaldehyde (HCA)                                     Parts                                                                   AHM [sic]                                                                           HCA    Visc.                                                                            -20° C.                                                                       0° C.                                                                      +10° C.                                                                       +20° C.                              __________________________________________________________________________    90    10        1      1   1      1                                           80    20        1      1   4      4                                           70    30        1      4   6      6                                           60    40     30 1      5   6      6                                           50    50     40 1      5   6      6                                           40    60        2      6   6      6                                           30    70        5      5   6      6                                           20    80     100                                                                              1      5   5      6                                           10    90        1      4   5      6                                           __________________________________________________________________________    Mixture of 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydro-                         naphthalene (AHN) and benzyl salicylate (BSA)                                       Parts                                                                   AHN   BSA Visc.                                                                              -20° C.                                                                     0° C.                                                                         +10° C.                                                                     +20° C.                                __________________________________________________________________________    90    10       1    1      1    1                                             80    20       1    1      1    2                                             70    30       2    2      4    5                                             60    40       4    4      5    5                                             50    50       4    4      5    6                                             40    60  40   5    5      6    6                                             30    70  32   5    6      6    6                                             20    80       5    5      6    6                                             10    90       2    4      4    6                                             __________________________________________________________________________    Mixture of hexylcinnamaldehyde (HCA) and benzyl salicy-                       late (BSA)                                                                          Parts                                                                   HCA   BSA                                                                              Visc.                                                                              -20° C.                                                                     0° C.                                                                         +10° C.                                                                     +20° C.                                 __________________________________________________________________________    90    10      2    4      5    6                                              80    20      2    4      5    6                                              70    30      4    5      6    6                                              60    40      4    5      6    6                                              50    50 20   5    6      6    6                                              40    60 20   4    6      6    6                                              30    70      2    5      5    6                                              20    80      2    5      5    6                                              10    90      2    4      5    6                                              __________________________________________________________________________    Mixture of benzyl salicylate (BSA) and para-methoxyaceto-                     phenone (PMA)                                                                       Parts                                                                   BSA   PMA Visc.                                                                              -20° C.                                                                     0° C.                                                                        +10° C.                                                                     +20°  C.                                __________________________________________________________________________    20    80       2    2     4    4                                              50    50  17   2    5     6    6                                              66.6  33.3     4    6     6    6                                              80    20       2    6     6    6                                              __________________________________________________________________________    Mixture of hexylcinnamaldehyde (HCA) and para-methoxy-                        acetophenone (PMA)                                                                  Parts                                                                   HCA   PMA Visc.                                                                              -20° C.                                                                     0° C.                                                                        +10° C.                                                                     +20° C.                                 __________________________________________________________________________    80    20       4    6     6    6                                              60    40  15   4    5     6    6                                              40    60       4    3     5    5                                              20    80       1    2     2    4                                              __________________________________________________________________________    Mixture of 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydro-                         naphthalene (AHN), hexylcinnamaldehyde (HCA) and benzyl                       salicylate (BSA)                                                                  Parts                                                                     AHN HCA  BSA Visc.                                                                             -20° C.                                                                      0° C.                                                                       +10° C.                                                                      +20° C.                              __________________________________________________________________________    40  10   50      4     4    5     6                                           40  20   40      4     5    6     6                                           40  30   30  30  6     6    6     6                                           40  40   20      6     6    6     6                                           40  50   10  30  6     6    6     6                                           50   5   45      4     4    5     6                                           50  15   35  45  4     4    5     6                                           50  25   25      4     5    6     6                                           50  35   15  40  6     6    6     6                                           50  45    5      6     6    6     6                                           60  10   30      2     4    5     6                                           60  20   20      2     4    5     6                                           60  30   10      2     4    5     6                                           __________________________________________________________________________

Preparation of the eutectic mixtures

The preparation of the material mixtures which are stable in liquid formpresents no problems at all. Having one or more of the componentspresent in liquid form and directly combining them in the intended ratiohas proved particularly advantageous here. Since all individualcomponents are in liquid form directly after their synthesis, thepreparation of the eutectic mixtures directly by raw material producersis particularly energy-saving and simple.

However, it is also possible for the mixtures to be prepared by theusers themselves, by initially introducing premelted stable individualcomponents and mixing them in the intended ratio with crystallinematerials.

The addition of the liquid fragrance building blocks to the remainingformula is carried out without further pretreatment at room temperatureby simply pumping in or via metering valves controlled by a processcomputer. Parts of the perfume mixing process which were previouslyimpossible to automate for technical reasons can thus be automated.

The homogeneous final mixing is carried out in all cases after theaddition by a short stirring process or by circulation/pumping.

The odorless traditional solvents (diethyl phthalate, dipropyleneglycol, etc.) used in the traditional perfume process for predissolvingthe large amounts of solid prove to be superfluous if preliquefied solidmixtures are used. Since in this case the process is carried out at roomtemperature, the components of the perfume formula which are sensitiveto oxidation or polymerization or are readily volatile can be added inany order which can be freely chosen.

Since only liquids which can be homogenized without any problems at allare used in the method proposed according to the invention, considerableincreases in capacity compared with traditional perfume mixing processesare permitted.

The liquid eutectic mixtures proposed according to the invention andcomprising the stated individual components can be used as fragrancebuilding blocks in the following variations. ##STR1##

The above fragrance building blocks may be regarded as basic buildingblocks of a modern industrial perfume formula which, when used in thevery wide range of variations, account for about 20-50% of the totalformula or 70-90% of solids. All formula variations tested to date wereliquid at room temperature.

The preparation of further successful fragrance building blocks based onthe proposed basic building block is possible by adding furthercomponents as follows, and is possible in all variations. ##STR2##

The proportion of these fragrance building blocks composed of a fewbasic components in all current industrial perfume formulas is between40 and 90%.

The other substances which are either liquid or are solid and to be usedin small amounts can thus be mixed without problems.

The ready-made perfume mixtures prepared by the method proposedaccording to the invention surprisingly prove to be "superstable atfreezing points of 0° to minus 20° C." even without solvent components.The expensive storage of ready-made perfumes in heated storage rooms canthus be avoided in the future without any quality risk.

We claim:
 1. A method of preparing a homogenous perfume mixture,comprising mixing a binary or ternary eutectic premix which is liquid atroom temperature with additional perfume components to form thehomogenous mixture, wherein the binary eutectic premix consistsessentially of two components selected from the group consisting of:a)6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene, b)α,n-hexylcinnamaldehyde, c) p-tert-butyl-α-methylhydrocinnamaldehyde, d)p-methoxyacetophenone, and e) benzyl o-hydroxybenzoate, and the binaryeutectic premix is present in an amount of 10-90%, and wherein theternary eutectic premix consists essentially of three componentsselected from the group consisting of: a)6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene, b)α,n-hexylcinnamaldehyde, c) p-tert-butyl-α-methylhydrocinnamaldehyde, d)p-methoxyacetophenone, and e) benzyl o-hydroxybenzoate, and the ternaryeutectic premix is present in an amount of 10-70%.
 2. A method ofpreparing a homogenous perfume mixture, according to claim 1, whereinthe additional perfume components comprise solid materials and themixture is further heated to liquify or dissolve the solid material. 3.A method of preparing a homogenous perfume mixture according to claim 2,wherein the mixture is maintained at a temperature between the meltingpoint of the eutectic premix and the melting point of the solidmaterial.
 4. A method of preparing a homogenous perfume mixtureaccording to claim 2, wherein the heat required to liquify or dissolvethe solid material is supplied by one or more of an ultrasonic ormicrowave generator.
 5. A method of preparing a homogenous perfumemixture according to claim 1, wherein the binary or ternary eutecticpremix are fragrance building blocks for a desired fragranceformulation, and the mixing includes combining two or more of the binaryor ternary eutectic premixes of different compositions to produce thedesired formulation.
 6. A method of preparing a homogenous perfumemixture according to claim 5, wherein additional perfume materials arecombined with the fragrance building blocks to modify the fragranceformulation.
 7. A method of preparing a homogenous perfume mixtureaccording to claim 1, wherein no solvents are added in the mixing, andthe addition of the binary or ternary eutectic premix and the additionalperfume components to the mixture is computer-controlled.
 8. A method ofpreparing a binary or ternary eutectic perfume premix consistingessentially of combining two or more components selected from the groupconsisting of:a) 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene,b) α,n-hexylcinnamaldehyde, c) p-tert-butyl-α-methylhydrocinnamaldehyde,d) p-methoxyacetophenone, and e) benzyl o-hydroxybenzoate, to therebyform the premix.
 9. A method according to claim 8, wherein no solventsare added to the premix.
 10. A binary or ternary eutectic perfume premixwhich consists essentially of two or more components selected from thegroup consisting of:a)6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene, b)α,n-hexylcinnamaldehyde, c) p-tert-butyl-α-methylhydrocinnamaldehyde, d)p-methoxyacetophenone, and e) benzyl o-hydroxybenzoate.
 11. A premixaccording to claim 10, wherein the premix is a binary mixture of two ofthe components.
 12. A premix according to claim 10, wherein the premixis a ternary mixture of three of the components.
 13. A premix accordingto claim 10, wherein the components comprise6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene andα,n-hexylcinnamaldehyde.
 14. A premix according to claim 10, wherein thecomponents comprise 6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthaleneand p-tert-butyl-α-methylhydrocinnamaldehyde.
 15. A premix according toclaim 10, wherein the components comprise6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene andp-methoxyacetophenone.
 16. A premix according to claim 10, wherein thecomponents comprise6-acetyl-1,1,3,4,4,6-hexylmethyltetrahydronaphthalene and benzylo-hydroxy-benzoate.
 17. A premix according to claim 10, wherein thecomponents comprise α,n-hexylcinnamaldehyde andp-tert-butyl-α-methylhydrocinnamaldehyde.
 18. A premix according toclaim 10, wherein the components comprise α,n-hexylcinnamaldehyde andp-methoxyacetophenone.
 19. A premix according to claim 10, wherein thecomponents comprise α,n-hexylcinnamaldehyde and benzylo-hydroxybenzoate.
 20. A premix according to claim 10, wherein thecomponents comprise p-tert-butyl-α-methyl-hydrocinnamaldehyde andp-methoxyacetophenone.
 21. A premix according to claim 10, wherein thecomponents comprise p-tert-butyl-α-methyl-hydrocinnamaldehyde and benzylo-hydroxybenzoate.
 22. A premix according to claim 10, wherein thecomponents comprise p-methoxyacetophenone and benzyl o-hydroxybenzoate.23. A premix according to claim 10, wherein the components comprise6-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene,α-hexylcinnamaldehyde and benzyl salicylate.